- Author: C. Scott Stoddard
- Posted by: Gale Perez
August 7, 2021
Bindweed is a headache not only for its persistent and pernicious growth habit and ability to reduce tomato yields, but also because it can physically stop a processing tomato harvester in the field. Vigorously growing vines can become entangled around the shaker and conveyor belts, requiring the equipment operator to shut down and manually clear out the foliage.
Several years ago, myself and other UC researchers conducted herbicide trials evaluating field bindweed control -- with marginal success. In a given year and location, most of the registered herbicides in tomatoes gave only temporary suppression – about 40 – 80% bindweed control at 8 weeks after transplanting. Best results were observed where herbicides were stacked: trifluralin (Treflan) pre-plant incorporated followed by rimsulfuron (Matrix) post. Glyphosate helped in situations where the bindweed emerged early and could be applied before transplanting (Figure 2).
Earlier this year, I was asked to summarize the effects of weeds on processing tomato yield. This made me go back and look at this work, but with a slightly different emphasis: impact of weed control (or really, lack of weed control) on yield. To increase the size of my dataset, I also included data from trials done at UC Davis. Where I had data for both yield and weed control in good, replicated trials, I performed a regression analysis comparing % weed control and % relative yield (relative yields remove the year-to-year and location variability). In the end, I used 4 trials from 2012-13 (Table 1).
Surprisingly, these data suggested that where bindweed dominated, it did not have a big impact on processing tomato yield. Even with just 50% control 8 weeks after transplanting, potential yield was 88-95%. This may have occurred because bindweed does not shade out the tomato canopy nearly as much as some of the common annual weeds. However, when tall broadleaf weeds dominated, such as pigweed, nightshades, and lambsquarters, yields dropped rapidly. I had some plots with a 99% yield drop if these weeds were allowed to grow all season. In this situation, the weeds towered over the tomato canopy.
Literature cited:
Van Wychen L (2019). 2019 Survey of the most common and troublesome weeds in broadleaf crops, fruits & vegetables in the United States and Canada. Weed Science Society of America National Weed Survey Dataset. Available: https://wssa.net/wp-content/uploads/2019-Weed-Survey_broadleaf-crops.xlsx
- Posted by: Gale Perez
Field Bindweed with Dr. Lynn Sosnoskie
Dr. Lynn Sosnoskie may have moved across the country to Cornell, but she is still interested in finding new and better ways to kill field bindweed. We discuss tips and tricks for tackling this pesky invader, but don't worry: if you can't get in control, your orchard canopy will eventually shade it out. Eventually.
https://www.growingthevalleypodcast.com/podcastfeed/2020/8/25/field-bindweed-with-lynn-sosnoskie
Here are two other weed science podcasts:
Old and New Perennial Weeds with Dr. Brad Hanson
In this short episode, Phoebe Gordon chats with Dr. Brad Hanson, Weed Specialist with UC Davis. They talk about perennial weed management, as well as two species that have recently become problematic in orchard crops: alkaliweed and threespike goosegrass. We don't know a lot about either, but Brad and other UC weed scientists are actively looking into management.
Herbicide Resistant Weeds with Kurt Hembree
Our first episode features an interview with Kurt Hembree, the Weed Management Advisor for Fresno County. We discuss herbicide resistance in weeds, and how to prevent herbicide resistance from emerging in your orchard, and more!
https://www.growingthevalleypodcast.com/podcastfeed/2018/6/1/orchard-floor-management
Original source: Growing the Valley Podcast website (https://www.growingthevalleypodcast.com/)
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- Author: Lynn M. Sosnoskie
Field bindweed (Convolvulus arvensis) is a perennial vine native to the Mediterranean region of Europe and Northern Africa that has become naturalized throughout much of the world. The species can reproduce vegetatively (through the spread of rhizomes) and via seed production. Field bindweed seedlings can be distinguished from emerging perennial vines by the presence of two square- to kidney-shaped cotyledons. Leaves are arrow-shaped and alternate along the developing stem. The true leaves of seedlings resemble those on mature vines (just being smaller in size to start). Within six weeks of emergence, the seedlings have developed a taproot and a significant number of lateral roots. For more information about field bindweed, please see UC IPM's web-page: http://ipm.ucanr.edu/PMG/WEEDS/field_bindweed.html. A PDF file of the images in this blog post is included at the end of this article, following the pictures.
Figure 1. The cotyledons of field bindweed are mostly square- to kidney-shaped.
Figure 2. Young field bindweed leaves resemble those of adult plants in that they are both arrow-shaped.
Figure 3. Field bindweed seedling.
Figure 4. Perennial bindweed vine on the left as compared to a newly emerging seedling on the right (note the presence of box-shaped cotyledons on the seedling).
Field bindweed ID
- Author: Lynn M. Sosnoskie
Field bindweed (Convolvulus arvensis) is a perennial plant in the Convolvulaceae family (which is also the family of dodder (Cuscuta spp.), morningglories (Ipomoea spp.), and alkaliweed (Cressa truxillensis)). The species possesses an extensive root network (vertical roots are reported to reach depths of 10 to 20 feet or more), although the majority of the underground biomass is in the top 1 to 2 feet of soil. Individual field bindweed plants produce multiple creeping vines that can grow up to 6 feet in length.
Figure 1. Field bindweed vines.
Native to the Mediterranean region and Western Asia, field bindweed is presumed to have been brought to the United States (in 1739) as a seed contaminant. The species moved westward and was officially documented in the state of California (San Diego County) in 1850. By the first quarter of the twentieth century, EW Hilgard (The Weeds of California, 1891) and FT Bioletti (The Extermination of Morning-glory, 1911) had proclaimed the species to be the most troublesome weed in the state.
Figure 2. Field bindweed (lower right) is in the same family as dodder (top) and alkaliweed (lower left). Photo by Lynn M. Sosnoskie.
Bindweed reproduces both by seed and vegetatively. Plants produce white to pinkish/purple trumpet-shaped flowers (1 inch in diameter to 1 inch in length) beginning in April and continuing through September in California (depending on latitude). Flowers open during the day and close tightly at night into a twisted tube. Seeds are approximately 1/8th of an inch long, black in coloration, shaped like an orange wedge, and produced in a papery capsule. Although estimates vary dramatically, it has been reported that bindweed infestations can produce between 20,000 and 20,000,000 seeds per acre.
Figure 3. Field bindweed flowers can be white to pinkish/purple in coloration. Photo by Lynn M. Sosnoskie.
Figure 4. Field bindweed seeds are dark brown to black in color, shaped not unlike orange wedges, and are held in papery capsules. Photo by Lynn M. Sosnoskie.
The germinability of freshly produced bindweed seed is highest 20-30 days after pollination; changes in seed moisture content and the permeability of the seed coat result in a dormancy that requires scarification to overcome. This hard-seededness is one reason bindweed is so enduring in fields. Although viability does diminish with time, field bindweed seed has been shown to persist in the soil for 20 to 30 years. Bindweed seed has been shown to germinate under a wide range of temperature conditions (between 41 F and 104 F with an optimum temperature around 86 F. Field bindweed germination and emergence is also impacted by burial depth: results from multiple studies have suggested that most new plants are developing from depths of 2 inches or less. Field bindweed plants begin to develop their extensive system within 4 to 6 weeks of emergence. This includes the development of latent buds that generate rhizomes from which new crowns arise.
New bindweed plants can also develop following the fragmentation of the root system of a parent vine. Roots are brittle and infrequent mechanical disturbance may serve to disseminate rhizome pieces around a field. According to published reports, the most regenerative root and rhizome tissues appear to arise from pieces derived from the top 12 inches of soil. Fragment size can also influence regenerative success; root portions longer than 1" in length will enhance establishment potential.
Figure 5. A newly germinated bindweed seedling (note the presence of cotyledons (seed leaves)). Photo by Lynn M. Sosnoskie.
Figure 6. Exhumed root system of a young field bindweed plant displaying lengthening and differentiating root buds and the development of a new crown. Photo by Lynn M. Sosnoskie.
The biology of field bindweed can directly impact how easily it is controlled by physical and chemical control measures. The extensive root system and regenerative potential of field bindweed necessitate frequent/continuous cultivation to exhaust nutrient reserves. Results from Kansas trials conducted in the mid 20th century suggest that soil disturbance every 2 to 3 weeks for 2 years is required to eradicate the perennial vines.
Figure 7. Results from studies conducted in the mid 20th century still form the basis for today's recommendations regarding field bindweed control with cultivation. Disturbance events need to occur every 2-3 weeks for up to 2+ years to exhaust the nutrient reserves stored in underground root and rhizome tissues.
The efficacy of foliar applications of glyphosate are also impacted by the species' roots...or, more importantly, the movement of photosynthates from above ground tissue to storage organs. The results of a study published in 1986 indicated that bindweed was more susceptible to glyphosate during the late spring/early summer months (when plants were flowering) as compared to early spring and late summer/early fall. There are multiple reasons for the differences observed in sensitivity, one of which is that the phloem mobile glyphosate was more readily translocated to meristematic tissues (including those in the root) where the herbicide inhibits the synthesis of aromatic amino acids.
Figure 8. Field bindweed is more readily controlled with glyphosate when it is vigorously growing and flowering. Glyphosate is phloem mobile and moves with photosynthates to the plants growing points (including underground meristems) where it inhibits the synthesis of aromatic amino acids.
Field bindweed is an increasing concern of growers in the Central Valley of California, especially those that are producing crops in reduced tillage/drip-irrigated systems. With a limited number of effective herbicides available (i.e. trifluralin in processing tomatoes, glyphosate in glyphosate-resistant agronomic commodities), the problem is likely not going to abate in the short term. Knowing what we do about the biology of bindweed (and how biology affects our ability to control this species), where do we go from here? The following considerations are just my opinions
• We need to discover/evaluate new strategies to increase the disruption/disturbance experienced by rhizomes. We need to do this both within and across crops (i.e. crop rotation).
• Can we manipulated bindweed biology to make the dormant root buds more sensitive to control measures?
• How does bindweed adopted to California and the southwestern United States differ from bindweed in the rest of the country? Should we assume that data generated in midwestern environments is appropriate for a California climate.
• Speaking of climate, how will variable weather impact bindweed growth, rhizome and bud dormancy, and subsequent control going forward?
This information was derived from a presentation presented at an extension event hosted by UCCE Fresno at the Westside Research and Extension Center in Five Points, CA, on August 15, 2018. A link to the pdf of the original slides is provided below.
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2018 Westside Bindweed Talk
- Author: Lynn M. Sosnoskie
In a recent blog post, Dr. Clyde Elmore discussed weed species changes in urban environments in response to the ongoing drought. One weed that can thrive under dry conditions is field bindweed, a significant weedy pest for homeowners, land managers, and farmers, alike.
NOMENCLATURE:
Field bindweed was first named by Linnaeus in 1753; its Latin binomial (Convolvulus arvensis) is derived from convolvere ("to roll together") and arvense ("in the field"). Which is pretty appropriate, if you ask me.
BINDWEED BIOLOGY
Field bindweed is a persistent perennial in temperate climates that can colonize a multitude of habitats including: roadsides, railways, pastures, cultivated fields, orchards and vineyards, lawns, and home gardens. Emerging vines may arise from germinated seeds (as evidenced by the presence of cotyledons, which are almost square but for rounded edges) or from underground stems called rhizomes (no seed leaves are present) (Figure 1). Field bindweed leaves average between 1/2 and 2 inches in length, are alternately arranged along the vine, and are arrowhead-shaped. The species displays some plasticity with respect to the growing environment; under ideal conditions, the leaves (and vines) will be larger and more robust than they might appear during times of drought. The vines are typically prostrate, although they will grow and twine up through flowers, crops, and shrubs.
Figure 1. Field bindweed seedling emerging (left) as compared to a vine emerging from over-wintering rhizomes.
Flowers are trumpet-shaped (resulting from the fusion of five petals) and are about 1 inch in diameter. Flowers are white to pink in coloration and last for a single day. Fun fact: a related species, Convolvulus tricolor, was included in Linneaus' flower clock. To find out more, do an Internet search for 'flower clock', 'circadian rhythm', and/or 'chronobiology'. Field bindweed seeds are produced in papery capsules with an average plant producing between 500 to 600 seeds (Figure 2). Individual seeds are 3-sided, brown to grey in color, and have hard, impermeable coats. This mechanically enforced dormancy ensures that seeds can survive for many years in soil.
Figure 2. Rounded capsules containing between 1 and 4 field bindweed seeds, each, along the length of a vine.
Field bindweed is less affected (than many other species) by drought conditions due to its deep and extensive root system. Although the majority of the species' lateral roots and rhizomes are found in the upper two feet of the soil surface, some vertical roots can extend to depths of 10 to 20 feet, or more.
Field bindweed can be easily mistaken for other closely related species, including: hedge bindweed (Calystegia sepium), wild buckwheat (Polygonum convolvulus) and numerous morningglory species (Ipomoea spp.). For more information regarding species identification/discrimination, please see the following websites:
King County, WA: http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/field-bindweed.aspx
Oregon State University: http://oregonstate.edu/dept/nursery-weeds/feature_articles/vines/vine_weeds.html
UC IPM: http://www.ipm.ucdavis.edu/PMG/WEEDS/morningglories.html
BINDWEED MANAGEMENT
Anyone who has attempted to manage field bindweed knows that the efficacy of any strategy (chemical, cultural, and physical) is dependent upon the size of your infestation, as well as the magnitude of your patience. The UC IPM webpage provides advice regarding field bindweed control. It is well worth a review.
In August/September 2015, we conducted two small studies to look at the efficacy of 'homeowner' or 'off the shelf' herbicides on field bindweed suppression (Figure 3). The herbicides included: 1) a mixture of citric acid and plant oils, 2) a soap of fatty acids, 3) glyphosate/glyphosate-based product, and a 4) mixture of auxinic active ingredients. All of the products were purchased at a local hardware store and, with the exception of two concentrates that required dilution, all were 'ready to use' (RTU). The glyphosate and 2,4-D/dicamba/MCPP products in Study 1 were diluted to 1 oz and 4.5 oz product/gallon, respectively. All of the products were applied to emerged bindweed vines (which were flowering at the time of application). Plants were treated 'until wet' (as suggested on the product labels), meaning that the herbicide solutions were beginning to run off of the leaves; none of the products provided soil-based residual/extended weed control.
Figure 3. Details about the two studies conducted in 2015 to evaluate RTU herbicides for field bindweed control.
Results are presented in Figures 4 and 5. In both studies the citric acid/essential oil mixture did not control perennial field bindweed more than 50% for up to 28 days after treatment (DAT). Although the fatty acid mixture controlled field bindweed 99% at 3 DAT, control dropped to 35% to 40% by 28 DAT. Both the citric acid/essential oil and fatty acid herbicides are considered 'contact' products, meaning that they are only active against the plant tissue that they come into contact with. In essence, these products burned only the green leaf and stem tissue that they were applied to. While these contact herbicides are likely to be effective at managing bindweed seedlings, perennial vines can draw upon stored root reserves and re-sprout.
The glyphosate and auxinic herbicide-based products acted more slowly (because of their systemic nature), but provided 99% control of field bindweed at 28 DAT. The one exception was the glyphosate-pelargonic acid herbicide in study number 2; although glyphosate must be translocated to its site of action before control can occur, pelargonic acid is a contact herbicide (hence the rapid burndown). Systemic herbicides are more likely to provide 'long-term' control of perennial weeds as these products will be moved away from the treated foliage and dispersed throughout the treated plants. For example, glyphosate is translocated to all growing points (i.e. both shoort and roots), where it interferes with amino acid synthesis; as a consequence, field bindweed treated with glyphosate will regenerate/recover more slowly.
Figure 4. Field bindweed control in study 1 from 3 DAT to 28 DAT. The blue line represents the citric acid/essential oil product, the orange line represents the fatty acid soap, the grey line represents the 2,4-D/dicamba/MCPP herbicide, and the yellow represents glyphosate.
Figure 5. Field bindweed control in study 2 from 3 DAT to 28 DAT.The blue line represents the citric acid/essential oil product, the orange line represents the fatty acid soap, the grey line represents the 2,4-D/dicamba/quinclorac herbicide, and the yellow represents glyphosate/pelargonic acid.
HERBICIDE PERFORMANCE AND SAFETY
Before choosing a herbicide, be sure to understand how and for how long the products will work. For perennial weeds, systemic herbicides will likely provide greater/longer suppression than contact products, although it is reasonable to expect that a single application may be insufficient for complete control. This is an important point to remember: herbicides are not always 100% effective. Herbicides may fail for many reasons including: poor spray coverage on large weeds, applications to stressed weeds, herbicide wash off, use of an ineffective active ingredient against the target species, etc. Herbicides, if used improperly, can cause damage to desirable species; anyone using herbicides should be aware of their selectivity and the conditions that can induce spray drift or volatility. And, as always, people using herbicides should be mindful to follow ALL instructions listed on the labels to ensure the safety of themselves, their family and pets, and the environment.